Java签到程序实现教程

class User {
    private String userId;
    private String name;

    public User(String userId, String name) {
        this.userId = userId;
        this.name = name;
    }

    // getter 方法
    public String getUserId() { return userId; }
    public String getName() { return name; }
}

class CheckInRecord {
    private String userId;
    private long timestamp;
    private String dateKey; // 格式如 "2024-04-05"，用于判断是否当天已签到

    public CheckInRecord(String userId) {
        this.userId = userId;
        this.timestamp = System.currentTimeMillis();
        this.dateKey = new java.text.SimpleDateFormat("yyyy-MM-dd")
                       .format(new java.util.Date());
    }

    public String getUserId() { return userId; }
    public String getDateKey() { return dateKey; }
    public long getTimestamp() { return timestamp; }
}

import java.util.*;

public class AttendanceSystem {
    // 存储每个用户每天的签到记录：key=userId, value=日期集合
    private Map();

    public boolean checkIn(String userId) {
        String today = new java.text.SimpleDateFormat("yyyy-MM-dd")
                       .format(new java.util.Date());

        // 获取该用户的签到日期集合
        Set checkedDates = userCheckIns.getOrDefault(userId, new HashSet<>());

        if (checkedDates.contains(today)) {
            System.out.println("今天已经签到过了！");
            return false;
        }

        // 添加签到记录
        checkedDates.add(today);
        userCheckIns.put(userId, checkedDates);

        System.out.println("签到成功！时间：" + 
                          new java.util.Date(System.currentTimeMillis()));
        return true;
    }
}

public class Main {
    public static void main(String[] args) {
        AttendanceSystem system = new AttendanceSystem();

        String userId = "U001";

        system.checkIn(userId); // 第一次签到
        system.checkIn(userId); // 重复签到，提示已签到
    }
}